1. Field of the Invention
The present invention generally relates to tape measures and, more specifically, to a tape measure with an improved tape braking control mechanism.
2. Description of the Prior Art
Tape measures of the type that has a spring loaded tape cartridge including a coilable tape have been widely accepted in the marketplace for a variety of consumer and professional uses. Such spring loaded tape allows the tape to be withdrawn or pulled outside of the housing of the tape measure, a power spring employed in connection with the tape cartridge providing a retracting force tending to draw the metal tape rule back into the case and rewind it or re-coil it about the spool or bobbin from which it was withdrawn. However, depending on the size of the tape, the extent to which the tape was withdrawn and the strength of the spring, a tape can be retracted with such force and velocity that the tape can cause injury to a user or others standing by and also can cause damage to the tape itself. With such tape measures, when the tape is inadvertently released and there is no longer any tension to counteract the retraction force of the spring, the tape initially starts to recoil quite vigorously. However, unless the user quickly grips the tape and gains control over it, the tape will tend to accelerate and gradually even increase its speed. The danger of attempting to grasp the moving tape is that the relatively sharp edges of the tape can cause cuts unless the hand of the user is protected, such as by a glove. Also, because long lengths of metal tape frequently do not have the ability to remain straight but bend along different portions thereof, a rapid retraction of the tape can also cause damage to the tape by kinking the same and, in some instances when the tape is violently retracted, the tape can actually fracture or become severed. During such instances when the tape is retracted at a very high speed, there is always the danger that the free end of the tape will be randomly propelled in space and may also injure a user or bystander by the random and violent movements of the tape. Repeated retractions of this type may also reduce the service life of the tape measure.
Means have been used in known tape measures for locking and/or slowing down retracting tapes. Typically, this involves applying pressure to a locking button exteriorly mounted on the housing. The locking button is normally mounted for movements over a limited range between tape releasing and tape locking positions. In such instances, the manually actuated button is coupled or linked to a mechanism in the housing for slowing the retracting tape or holding it in place, the movement of the button to the locking position causing a member within the housing to come into contact with the tape. However, such arrangement is not always satisfactory and can be inefficient. Additionally, the application of an internal member into pressure abutment against the face of a tape can also cause such surface to become scored and, in time, remove enough of the markings or measurement indicia to render the tape measure less useful.
In order to address some of the aforementioned problems, a tape measure is disclosed in U.S. Pat. No. 5,531,395 for a stopping device for tape measures. The tape measure is provided with a tape roller equipped with an inner helical spring and an outer tape measure. A plurality of mounting pieces are provided on the internal surfaces of the housing for supporting a stopping spring. The stopping spring is released from the outer stopping rim of the roller, allowing the tape to be automatically retracted using the tension of the helical spring of the tape roller. Release of the locking button allows the tension of the helical spring to return to its initial position, pressing against the outer stopping rim on one side of the tape roller and thus providing the means for stopping the tape roller. In the disclosed arrangement, however, it is clear that the stopping action is achieved by wedging a free end of a locking button extension between a mounting piece and a mounting rod, the extension being somewhat deformed and wedged to provide some measure of friction between the contacting elements. Because of the manner of construction, the button extension may find it difficult to remain in the locked position, particularly against the action of the spring which tends to return the button to its normal, releasing position. Also, inadvertent pressure on the button, which would tend to relax the same, could also inadvertently release the button.